In a closing method, a work piece constituted by a metal pipe material is rotated, and while heating the work piece, a die is pressed against the work piece such that the work piece gradually approaches the die and is subjected to plastic deformation.
A closing machine for performing this closing operation comprises an outer diameter chuck that grips an outer peripheral surface of the work piece, and a chuck spindle that drives the outer diameter chuck to rotate together with the work piece. The outer diameter chuck grips the work piece, which is introduced via a conveyor or the like, and drives the work piece to rotate in a predetermined position. The closing machine closes the work piece into a predetermined shape corresponding to the die by pressing the rotating die against the work piece that is rotated by the outer diameter chuck.
This closing method and closing machine are disclosed in JP2002-153930.
The work piece, which reaches a high temperature of 1000° C. or more upon implementation of the closing operation, is cooled by a cooling device and then press molded using a closing press-molding device.
A conventional cooling device cools the work piece by pouring cooling water over the work piece.
However, since the conventional cooling device cools the work piece by pouring cooling water over the work piece, it is difficult to cool the bottom portion of the work piece, which has reached a high temperature due to the closing operation, quickly and evenly, and as a result, the tact time required to cool a single work piece increases.
It is therefore an object of his invention to provide a cooling method and a cooling device with which the bottom portion of a work piece that has reached a high temperature due to a closing operation can be cooled quickly.